SC 330: Appeared in 1941 or 1942. Ran from SC 5-33 (current US 301-US 321 north split) southeast to SC 641 just inside Colleton County, a distance of 9 miles. The easternmost couple miles was a renumbering of SC 643, but the rest was new primary routing.
In 1948, SC 330 was downgraded to S-5-31 and S-15-37.

SC
331 not currently assigned

Previous SC 331's:

SC 331 #1:Appeared in 1925 or 1926 as new primary routing. Ran from SC 33 (current US 321) Sycamore west through Allendale to Allens Landing at the Savannah River.
SC 331 was extended over the river to connect with GA 73 in 1940.
In 1942, SC 331 was renumbered as SC 73. Today it is US 301 from the Georgia Line to Allendale, and SC 641 from Allendale to Sycamore.

SC 331 #2: A new SC 331 was created in 1942, running from SC 631 (current SC 3) in southwestern Allendale County east 4 miles, then due north 5 miles to end at SC 361 west of Barton.
In 1948, SC 331 was downgraded to S-3-41, a tiny bit of S-3-49, and S-3-203.

Creation: Created in 1939 as new primary routing. Ran only from SC 33 (current US 301-601) Cope to SC 5 (current US 321) Norway.
Adjustments: In 1941 or 1942, SC 332 was extended in both directions: west to SC 4 near Springfield, and east to SC 36 (current S-38-39).
In 1948, SC 332 east was truncated to run only from SC 4 to Norway. Norway to Cope became an unknown secondary route, and Cope to SC 36 was downgraded to S-38-63.
SC 332 was re-extended to Cope in 1949.
Improvements: Paved from Norway to Cope in 1949. SC 4 to Norway was paved in 1950; no multilane sections
Comment: SC 332's western half is a nicely aligned route that can be used along with SC 400 as an alternate to SC 4.

Creation: Appeared as a ressurected state route in 1949, running as it does now.
Adjustments: SC 333 first appeared in 1939, running as it does now, except its endpoints were SC 5 and SC 63.
In 1940, SC 333 was extended in both directions: west in a sweeping 11-mile loop over to Shirley, then back aroud southeast to end at SC 5 (current US 321) Garnett; east to the Jasper County Line.
In 1941 or 1942, SC 333 was extended east again to end at SC 631 (current SC 3) west of Grays. This brought SC 333 to a total length of 23 miles.
In 1948, SC 333 was downgraded to S-25-20, S-25-25, S-25-26, and S-27-17 before being born again in its present form in 1949.
Improvements: Paved in 1949; no multilane sections
Comment: I drove SC 333 in 1996. It is a simple rural connector between two small towns.

SC
334 not currently assigned

Previous SC 334's:

SC 334: Appeared in 1940 as new routing. Ran from SC 5 (current US 321) Govan east across SC 33 (current US 301), then southeast to SC 36-364 jct (current US 601/S-5-21 jct) Ehrhardt.
In 1941 or 1942, SC 334 was extended west to SC 64 at the Salkehatchie River east of Barnwell, for a total of 22 miles.
SC 334 was downgraded to S-6-36, S-5-22, and S-5-23 in 1948.

SC
335 not currently assigned

Previous SC 335's:

SC 335: Appeared in 1939 as new routing. Ran from SC 5 (current US 321) Fairfax 6 miles east to the Hampton-Allendale Line.
In 1940, SC 335 was extended in both directions: east to SC 361 (current S-25-13/S-25-43 jct) in Northern Hampton County; south along SC 5, then west to SC 361 (current S-3-23) near Barton.
The 12 miles of SC 335 were downgraded to S-3-21, S-3-18, and S-25-13 in 1948.

Creation: Appeared as a new state route in 1938. Ran from SC 33 (current US 321) Tillman to US 17-SC 36 (current US 17-278) Ridgeland.
Adjustments: SC 336 was extended east to SC 462 Old House in 1997, replacing a piece of US 278.
Improvements: Paved in 1939; no multilane sections
Comment: SC 336 can be used as an alternate route from I-95 to Hilton Head, via SC 462 and SC 170.

SC
337 not currently assigned

Previous SC 337's:

SC 337: Created in 1940 as new primary routing. Ran from SC 631 (current SC 3) at the Gaul Creek Bridge northeast 12 miles to SC 28 (current SC 125) Allendale.
In 1948, the 11 miles of SC 337 were downgraded to S-3-22.

SC
338 not currently assigned

Previous SC 338's:

SC 338: Appeared in 1940 as new routing. Ran from SC 28-361 (current US 278) Brunson northeast to SC 335 (current S-25-13) near he Allendale-Hampton Line, a total of 5 miles.
In 1948, SC 338 was downgraded to S-25-28.

SC
339 not currently assigned

Previous SC 339's:

SC 339: Appeared in 1940 as new routing. Ran from SC 336 Ridgeland west 4 miles to today's S-27-115.
In 1941 or 1942, SC 339 was extended west as new routing to SC 5 (current US 321) Tarboro, for a total of 11 miles.
In 1948, SC 339 was downgraded to S-27-14 and S-27-22. The county atlas book shows the western 7 miles as still unpaved today.